They’re lighting up the New Orleans Superdome, helping us sleep better, dressing us fashionably, delighting our taste buds, giving us a better way to work, and scoring us tickets for opening day. These young entrepreneurs join the likes of Facebook’s Mark Zuckerberg, Mint.com’s Aaron Patzer, and Learnvest’s Alexa von Tobel as members of our annual 30 Under 30. But even those esteemed alums can’t claim to have cleared a higher hurdle than has this year’s class. We received 650 applications (up from 400 last year), which means that getting into Harvard was easier than landing a spot on this list.

Choosing our honorees gets tougher every year. We began the process in January with a two-month call for nominations. Staff members read each online application and chose approximately 160 promising ones to send off to our judging panel, comprised of a select few entrepreneurs from our Inc. community, some 30 Under 30 alums, a venture capitalist or two, and some folks from leading tech accelerator programs. We were looking for entrepreneurs who were, well, cool.

It’s a tough word to define, but we know it when we see it. Cool could involve inventing an innovative new product or service (like Julia Hu of Lark or Justin Rosenstein and Dustin Moskovitz of Asana), making a big impact in an existing industry (like Nasty Gal’s Sophia Amoruso), beating out huge competitors by being nimble and creative (like Gary Solomon’s eponymous company), or maybe just selling more lobster rolls than seems humanly possible. Two rounds of judging later, and after a good amount of due diligence from our reporters, a final list emerged. And what an amazing list it is!

Collectively, this year’s honorees racked up more than $300 million in revenue in 2012, employ approximately 2,500 people, and have raised in excess of $366 million in outside investment capital to grow their companies. These are not lemonade stands, folks. In fact, five of our honorees were also on the Inc. 5000 list last year. But 30 Under 30 has never been just about revenue.

Sure, we love companies that are growing quickly and doing their part to put a dent in the unemployment statistics. That’s cool, in our book. But so is saving an iconic skate boot company from extinction (Adoni Group), running experiential learning summits in Africa (Think Impact), developing a plugless power system for electric vehicles (Evatran), or creating one of the biggest Harry Potter fan sites in the world (Spark Media). Their individual stories are compelling, but the entire list tells a few stories as well. Some of the noteworthy trends that jumped out at us were:

1. B-to-B tech companies are hot.

If there’s a single category of companies that dominates our list, this is it. There’s a growing need among institutions of all sizes to better leverage technology to manage all aspects of their businesses, and those needs are being met by young start-ups. For instance, HireVue offers a cloud-based platform that enables hiring teams to browse, watch, rate, and share video interviews with job candidates. OrgSync has created an online community management platform tailored specifically to the higher education market, and BandPage enables musicians to engage their fans across the Web. In fact two of the largest companies on our list-- Yodle and Mutual Mobile--are in the B-to-B tech space.

2. Hardware is cool again.

We were thrilled that such a large number of our applicants were making cool devices for work and play. Lark (one of the two hardcore tech companies on our list run by women), makes wearable wellness monitors, Orbotix makes a robotic ball called Sphero that is tablet or smartphone-controlled, and Leap Motion stole the show at SXSW this year with a new 3D motion control device that allows users to control their computers by pointing a finger or waving a hand.

3. Brick and mortar is alive and well.

While the high profile tech companies get a lot of attention, remember that awesome young entrepreneurs are making an impact in just about every industry imaginable. Uptown Cheapskate’s Chelsea Sloan, for instance, carved out a highly lucrative niche for herself by building a chain of branded consignment shops, bringing a professionalized sensibility to a fragmented industry. And Luke Holden, horrified by what passed for a lobster roll in New York City, built a growing fleet of food trucks and a chain of restaurants that bring an authentic Maine lobster shack experience to city dwellers.

4. This generation starts young and keeps going.

We hear it often, but it never ceases to amaze us: "I started my first company when I was 12." Whether they delivered bottled water in a Radio Flyer wagon, sold used golf balls, or built websites just for fun, quite a number of our honorees this year showed early signs of entrepreneurial mojo. What better way to insure an ongoing supply of Jolly Ranchers? Some, such as Gary Solomon (Solomon Group), Rebecca Hough (Evatran), Jordan and Jensen Adoni (The Adoni Group), and Chelsea Sloan (Uptown Cheapskate), grew up in entrepreneurial households and stated their companies under the watchful eyes of successful parents. Others were conceived of or started in dorm rooms (Wireless Communications and Course Hero, for instance). Suffice to say that the majority of our honorees were well on their way to building multi-million companies while most of their peers were going to keggers and polishing up their resumes. Not surprisingly, some are even on their second or third company.

We think you’ll agree that the bar has been raised quite a bit since we launched our first 30 Under 30 Coolest Entrepreneurs list back in 2006, when a young upstart named Mark Zuckerberg had just begun to change our lives forever with a company that was then just two years old. Which of the companies on this year’s list do you think will have a similar impact? Check out their profiles and videos here, and vote for your favorite.